A Laboratory Method for Rearing Catolaccus Hunteri (Hymenoptera: Pteromalidae), a Parasitoid of the Pepper Weevil (Coleoptera: Curculionidae)

Scientiﬁc Notes 191

A LABORATORY METHOD FOR REARING CATOLACCUS HUNTERI (HYMENOPTERA: PTEROMALIDAE), A PARASITOID OF THE PEPPER WEEVIL (COLEOPTERA: CURCULIONIDAE)

EMILY VÁSQUEZ1, DAVID DEAN2, DAVID SCHUSTER1 AND PAUL VAN ETTEN1 1University of Florida, IFAS, Gulf Coast Research & Education Center, Wimauma, FL 33598

2Florida Department of Agriculture and Consumer Services, Fruit Fly Identiﬁcation Laboratory, Palmetto, FL 34221

The pepper weevil, Anthonomus eugenii Cano, Plastic Packaging, Inc., Menasha, WI) for presen- is a serious pest of cultivated Capsicum spp. pep- tation to parasitoid adults. This method was de- pers in the southern United States, Hawaii, Mex- veloped for exposing A. grandis grandis larvae to ico, Guatemala, Honduras, Costa Rica, and Puerto ovipositing C. grandis (Cate 1987) and was mech- Rico (Schuster et al. 1996). Eggs are deposited in anized for mass production (Roberson & Harsh flower buds and fruit, where larvae and pupae 1993). Methods also were developed for producing complete their development. Infested buds and C. maculatus larvae in pieces of garbanzo beans fruit often abscise, but larvae and pupae can com- (chick peas), Cicer arietinum L. (Leyva et al. plete development if fallen buds and fruit do not 2002). The pieces were not large enough for lar- desiccate. Yield losses can reach 90% in Florida, if vae to complete their development within, thus the weevil is not controlled (Schuster & Everett forcing the larvae to exit the bean pieces. The lar- 1982). Broad spectrum insecticides have been vae then were easier to collect prior to encapsula- used most often to manage the pest but may lead tion. This method had been used successfully to to unintended consequences, including insecticide rear C. hunteri in the laboratory. Life history pa- resistance and outbreaks of non-target pests. Bio- rameters including pre-oviposition period, ovipo- logical control could be an alternative or adjunct sition period, adult longevity, fecundity, and egg to insecticides in managing the pepper weevil. to adult development period of C. hunteri on A. eu- At least three species of predators and seven genii were found to be the same whether the par- species of parasitoids have been reported to at- asitoid had originally been reared on either tack the pepper weevil (Riley & King 1994). The C. maculatus or A. eugenii (Seal et al. 2002). Col- most abundant parasitoid recovered from the lecting larvae and encapsulating them in Para- pepper weevil in Florida was Catolaccus hunteri film represents extra investments in time and Crawford (Hymenoptera: Pteromalidae) (Riley & equipment. Therefore, a method was developed Schuster 1992). While natural enemies generally for rearing C. hunteri on C. maculatus larvae di- are regarded as contributing little to control of rectly in garbanzo beans. the pest (Elmore & Campbell 1954), 50% parasit- Two colonies of C. maculatus were maintained ism of pepper weevil larvae by C. hunteri was ob- in a room at a temperature of about 27°C, relative served in fallen jalapeno buds and over 20% par- humidity of about 60% and a photoperiod of asitism in fallen bell pepper buds (Schuster et al. 14L:10D. The colonies were maintained on black- 1988). Augmentative releases of C. hunteri on al- eyed peas, Vigna unguiculata (L.) Walp., and on ternative host plants during the summer off-sea- garbanzo beans. The black-eyed peas were used to son and on pepper at the initiation of flowering maintain the colony of C. maculatus and the gar- have resulted in reduced or delayed damage by banzo beans were used for exposing C. maculatus weevil larvae (Schuster unpublished data). Be- larvae to the C. hunteri parasitoid. cause C. hunteri has shown potential for bio-con- Three times a week, six narrow-mouth 800-ml trol of the pepper weevil, a method of rearing the “Mason” glass jars (Ball Corporation, Muncie, IN) parasitoid in the laboratory is needed. were filled with 300 g of black-eyed peas each. A commercial diet for rearing pepper weevil About 100 C. maculatus adults were collected larvae is available (Bio-Serv, Entomology Divi- with an aspirator connected to a vacuum pump sion, Frenchtown, NJ); however, the diet was not and were deposited in each jar, which then was used due to low egg hatch (Toapanta 2001). Be- sealed with a screen, filter disc, and metal ring. cause rearing the pepper weevil in pepper fruit is These jars were stored upright. A new generation time and space consuming, an alternative host of bruchid adults emerged about every 30 d. was sought. The cowpea weevil, Callosobruchus Three times a week, ca. 400 C. maculatus maculatus Fabricius (Coleoptera: Bruchidae), adults were collected with an aspirator and put was shown to be a suitable factitious host for rear- into each of ten 800-ml glass jars that contained ing Catolaccus grandis (Burks) (Rojas et al. 1998), 300 g each of garbanzo beans. The C. maculatus a closely related parasitoid of the boll weevil, adults were removed 48 h later by placing the A. grandis grandis Boheman. The C. maculatus beans and bruchids on a metal sieve placed in the larvae were encapsulated in Parafilm® (Pechiney large opening of a 25-cm diam galvanized funnel,

192 Florida Entomologist 88(2) June 2005

the narrow end of which was attached to a wet/ ery Monday, Tuesday, and Wednesday, two trays dry vacuum cleaner. The vacuum was operated were placed in each of two oviposition containers until all C. maculatus adults were drawn through consisting of No. 6 (2.8 liter) plastic jars (Newell the sieve. The beans then were returned to the Rubbermaid Co., Wooster, OH) laid on their sides jars, which were laid on their sides. In about 21 d, (Fig. 1b). Water was provided by inserting two wa- the hatching larvae were 4th instars, the lifestage ter-filled, cotton-plugged 1-dram vials through used previously for parasitism (Rodriguez-Leyva two 1.3-cm diameter holes in the upper surface of et al. 2000). The larvae form pupation cells and each container. A cloth sleeve was attached to the chew an emergence hole, leaving only the integu- mouth of each container and was sealed with a ment of the bean. These opaque “windows” can be rubber band when not in use. Drops of honey were seen readily and aid in the selection of beans with placed on the inside top of the containers to pro- 3rd instars present. These jars were moved to the vide food and were replenished when consumed C. hunteri rearing room, which was maintained by the parasitoids. About 50 female and 50 male under the same conditions as the C. maculatus parasitoids were introduced into each oviposition rearing room. container. The trays in the containers were The beans were placed in trays (9 × 8 × 2 cm) changed three times a week for 26 days, at which with 115-125 beans in each tray. The trays were time the oviposition containers were disassem- plastic strawberry baskets with the sides bled and cleaned for re-use. trimmed to 2 cm high (Fig. 1a). Corks were glued The beans that had been exposed 2-3 days to to the bottoms of the trays to elevate them, thus parasitoids were placed in No. 3, 2.4-liter rectan- allowing more accessibility of the female parasi- gular, plastic containers (Newell Rubbermaid Co., toids to the beans on the bottoms of the trays. Ev- Wooster, OH) with screen covered square holes cut in the lid to allow ventilation but prevent es- cape of emerging C. maculatus adults. The beans were divided into three containers and each container was placed individually in Plexiglas® (Ato- fina Chemicals, Inc., Philadelphia, PA) incubation cages (30.5 × 30.5 × 30.5 cm) with a cloth sleeve on one end. Two sides of the cage were covered with organdy fabric to allow ventilation. After about 7 d, adult parasitoids began to emerge and were collected with a vacuum pump aspirator. The garbanzo beans were sifted to re- move C. maculatus adults. The beans were then placed on a wax paper-lined fiberglass lunchroom tray (45 × 35 cm), one layer deep and the trays were placed on the shelves of an emergence box (Fig. 2a). The emergence boxes were constructed of wood and had 4-8 shelves with individual, seal- able doors for each shelf. The shelves did not ex- tend to the back of the emergence box and the bean-filled trays were not placed on the shelf all the way to the back. Thus, an open space was cre- ated at the back of the box from the bottom to the top. At the top of this open space, a hole (5 × 20 cm) was cut and covered with metal window screen that allowed passage of C. hunteri but pre- vented that of the C. maculatus adults. A Plexi- glas collection chamber (32 × 32 × 21 cm) (Fig. 2b) was attached to the top of the emergence box over the screen-covered slot. The sides of the Plexiglas box had cloth sleeves installed, allowing access for collecting parasitoid adults with a vacuum pump aspirator. Two water-filled, cotton-plugged vials were placed in the bottom of the Plexiglas box and honey was streaked on the inside of the top and front. Both were replenished as needed. Fig. 1. Strawberry basket (a) for exposing garbanzo Trays were replaced within the emergence box beans with 4th instar Callosobruchus maculatus in ovi- every 23 days as new parasitoid-exposed, C. mac- position containers to adult Catolaccus hunteri (b) in the ulatus-infested beans were added. Once a week, laboratory. the Plexiglas box was thoroughly cleaned with

Scientiﬁc Notes 193

Anecdotal observations have indicated that bi- weekly releases of 1,500 C. hunteri along one edge of pepper ﬁelds of different sizes during the summer and fall fallow season resulted in reduced in- festations of the pepper weevil on pepper during the following spring season. In addition, experimental evidence on an organic farm indicated that weekly releases of the parasitoid at about 7,400/ha delayed the pepper weevil infestation (Schuster, unpublished data). In experimental plots, weekly releases of 1,500 C. hunteri in night- shade during the fallow, off-season followed by weekly releases at 7,400/ha in adjacent pepper in the spring resulted in 65-75% fewer pepper fruit infested by the pepper weevil. It is estimated that for an organic grower with a 1-ha block to make releases of 1,500 C. hunteri adults every 2 wk for 32 wks (16 releases during the fallow off-season) would cost about $250 in recurring expenses. To add additional releases of 7,400/ha would cost about another $76/wk during the early pepper season. Neither of these cost es- timates includes the cost of labor to release the parasitoid adults. The estimated cost for fallow season releases is probably cost effective but the in-season costs may be prohibitive; however, in discussions with organic producers, this latter cost may not be prohibitive in light of few effective alternatives for managing the pepper weevil. The current rate of parasitism in the C. maculatus host is about 40%. If the rate of parasitism could be increased without increasing production costs, the cost for releases of C. hunteri for managing Fig. 2. Emergence box (a) with tray of garbanzo the pepper weevil during the spring season could beans infested with 3rd instar Callosobruchus maculatus become more cost effective. that have been exposed to adult Catolaccus hunteri. As- This research was supported in part by USDA, pirating C. hunteri adults from the Plexiglas® collection Special Research Grants, Tropical/Subtropical chamber (b). Agricultural Research, and in part by the Florida Agricultural Experiment Station and approved for publication as Journal Series No. R-10607. Kimwipes® tissue (Kimberly-Clark Corp., Roswell, GA) moistened with water. SUMMARY Approximately 18,000 parasitoids were pro- duced weekly by these rearing methods with 26 Methodology was developed to rear Catolaccus oviposition cages. Start-up costs include about hunteri Crawford, a parasitoid of the pepper wee- $133 for 180 “Mason” jars for rearing the C. macu- vil (Anthonomus eugenii Cano), on an alternative latus; about $150 for a humidiﬁer to maintain RH host, the cowpea weevil (Callosobruchus macula- at 60% in the C. maculatus rearing room; about tus F.) in temperature controlled rooms at 27°C, $315 for 26 C. hunteri oviposition cages including 60% relative humidity and 14L:10D photoperiod. plastic jars, vials, cotton balls, honey, plastic berry Black-eyed peas, Vigna unguiculata (L.) Walp., baskets, corks, fabric (also used for incubation were used to maintain a colony of C. maculatus, cages), twine rope, and rubber bands; about $80 and garbanzo beans, Cicer arietinum L., were for each of 9 C. hunteri larval incubation cages; used to expose the C. maculatus larvae to C. hunt- and about $155 for labor and supplies to build each eri females. About 250 garbanzo beans containing of three adult emergence cages. About 22 h/wk 4th instar C. maculatus were exposed 48 to 72 h to were required in the maintenance of both the C. 50 female and 50 male C. hunteri. Parasitoid-ex- maculatus and C. hunteri colonies. About 4 kg of posed beans were held for about 7 days and were black-eyed peas and 6 kg of garbanzo beans were placed into emergence boxes with screened-cov- used each week. At $8/h for labor and $1.22/kg for ered slots, which retained C. maculatus adults in the peas and $0.90/kg for beans, the estimated re- the box but allowed C. hunteri adults to pass into curring cost of production was about $186/wk. a Plexiglas collection chamber. With an invest-

194 Florida Entomologist 88(2) June 2005 ment of about 22 h/wk, about 18,000 parasitoids ton Conf., Vol. 2, National Cotton Council of Amer- can be reared weekly at an estimated recurring ica, Memphis, TN. cost of $186/wk for labor and supplies. Start-up RODRÍGUEZ-LEYVA, E., J. L. LEYVA, V. GÓMEZ, N. M. costs for rearing containers and a rearing room BÁRCENAS, AND G. W. ELZEN. 2000. Biology of Cato- humidifier totaled about $1,800. laccus hunteri (Hymenoptera: Pteromalidae), a parasitoid of the pepper weevil and boll weevil (Coleoptera: Curculionidae). Ann. Entomol. Soc. REFERENCES CITED Amer. 93: 862-868. ROJAS, M. G., J. A. MORALES-RAMOS, E. G. KING, G. CATE, J. R. 1987. A method of rearing parasitoids of boll SALDANA, AND S. M. GREENBERG. 1998. Use of a facti- weevil without the host plant. Southwestern Ento- tious host and supplemented adult diet to rear and in- mol. 12: 211-215. duce oogenesis in Catolaccus grandis (Hymenoptera: ELMORE, J. C., AND R. E. CAMPBELL. 1954. Control of Pteromalidae). Environ. Entomol. 27: 499-507. the pepper weevil. J. Econ. Entomol. 47: 1141-1143. SCHUSTER, D. J., AND P. H. EVERETT. 1982. Control of LEYVA, E. R., V. G. TOVAR, N. M. B. ORTEGA, AND J. L. the beet armyworm and pepper weevil on pepper. LEYVA VAZQUEZ. 2002. Efecto de diferentes factores Proc. Fla. State Hort. Soc. 95: 349-351. sobre la cría de Callosobruchus maculatus (Co- SCHUSTER, D. J., D. G. RILEY, J. F. PRICE, AND J. B. leoptera: Bruchidae) para la producción de Catolac- KRING. 1988. Pepper weevil and sweetpotato white- cus spp. (Hymenoptera: Pteromalidae). Acta Zool. fly management on pepper. Univ. Fla., IFAS, Mex 86: 67-101. Bradenton GCREC Res. Rpt. BRA1988-19. RILEY, D. G., AND E. G. KING. 1994. Biology and man- SCHUSTER, D. J., D. R. SEAL, P. A. STANSLY, D. E. DEAN, agement of the pepper weevil Anthonomus eugenii C. CRUZ, AND R. ZAPATA. 1996. Prospects for inte- Cano (Coleoptera: Curculionidae): a review. Ento- grated management of the pepper weevil in the Car- mol. (Trends in Agric. Sci.) 2: 109-121. ibbean basin, pp. 71-72 In D. N. Maynard [ed.], Proc. RILEY, D. G., AND D. SCHUSTER. 1992. The occurrence of Natl. Pepper Conf., 8-11 Dec. 1996. Naples, FL. Catolaccus hunteri, a parasitoid of Anthonomus eu- SEAL, D. R., P. A. STANSLY, AND D. J. SCHUSTER. 2002. genii, in insecticide treated bell pepper. Southwest- Influence of temperature and host on life history pa- ern Entomol. 17: 71-72. rameters of Catolaccus hunteri (Hymenoptera: Pter- ROBERSON, J. L., AND D. E. HARSH. 1993. Mechanized omalidae). Environ. Entomol. 31: 354-360. production processes to encapsulate boll weevil lar- TOAPANTA, M. A. 2001. Population ecology, life history, vae (Anthonomus grandis) for mass production of and biological control of the pepper weevil, Anthono- Catolaccus grandis (Burks), pp. 922-923 In D. J. mus eugenii (Coleoptera: Curculionidae). Ph.D. dis- Horber and D. A. Richter [eds.], Proc. Beltwide Cot- sertation. University of Florida, Gainesville.